Tiny MCE in Joomla 3

Hello,

I am hoping to customize the buttons available in TinyMCE within my Joomla 3.2 website, but I cannot find the configuration files or where I would upload my plugins directory folder for this special button.

Does anyone know the structure and where this can be found? Lots of Joomla/Tiny MCE discussions but I haven't found anyone that articulates how to customize and add buttons in the latest version of Joomla.